The first step of this process will require a super admin with organization-wide (not chapter) access to create a new group that contains only the members of a specific chapter. In this example, I set up a "Texas Chapter Dedupe" group. Next, you will need to add all the supporters from within that chapter to the newly-created group, which can be done using the query tool. If you plan on deduplicating often, you might consider saving your query and turning the group into a smart group.

Next, you'll want to create a new role and restrict that role to the group you created:

After that, you will need to create a new Campaign Manager and assign only that newly-created role to it:

Make sure to change the Manager Type to "Normal" and only assign the single role. You will also need to select the available packages for this role, you can get by with just the following or add them all:

Once this step is complete, you can log in as the campaign manager (you will want to set a password for it, and use that with the email you assigned to the campaign manager) and run the deduplication process to return only duplicate supporters from your specific chapter.

If you have a lot of chapters, you may want to stick with the same naming convention for the campaign manager email, i.e. TexasDedupe@salsalabs.com, ArizonaDedupe@salsalabs.com and give them all the same password to make logging in and deduplicating easiest in the future.